The further preparation of inorganic cationic yeasts and some of their chief properties.

1. A method is described for replacing the intracellular K(+) of the yeast cell by Rb(+), Cs(+), Li(+) or Ca(2+) ions. In the formation of a calcium yeast it is necessary to proceed first through a sodium yeast (Conway & Moore, 1954) as in the formation of a magnesium yeast (Conway & Beary, 1962). This concludes the series of such yeasts in which almost all the usual K(+) is replaced by another cation, and for which the effect on the properties of fermentation, oxygen uptake and of growth are described. 2. Previous work has shown that all these inorganic cations that can be accumulated in quantity at pH7.0 are taken up by the same carrier, that the uptake of Mg(2+) is almost completely inhibited by anoxia and cyanide (0.2mm) and that in the uptake of Mg(2+) ions a practically equivalent amount of H(+) ions is excreted. It is suggested that these facts amount to a definitive demonstration that the carrier is a cytochrome.